1. Technical Field
The present invention relates to an image forming liquid cartridge, including a liquid container containing an image forming liquid, and an image forming apparatus equipped with the image forming liquid cartridge.
2. Related Art
An image forming apparatus employing a droplet discharge recording system, in which a liquid for printing such as ink is discharged in the form of droplets from a recording head, is known as image forming apparatuses such as printers; facsimile machines, copiers, plotters and combined machines thereof.
In some of the image forming apparatuses employing a droplet discharge recording system, a liquid is supplied from a printing liquid container to a recording head or a main tank that communicates with the recording head.
For example, an ink supply unit is known in which ink is supplied to a recording head from a liquid container via a hole formed by punching a sealing portion that seals an opening of the liquid container with a punch (see, for example, Japanese Patent Application Laid-Open (JP-A) No. 7-290717). In this apparatus, specifically, an ink hole is formed in the sealing portion made of a thin film, and the thin film is stretched with a punching unit to enlarge the ink hole, whereby ink is allowed to flow out through the opening of the liquid container.
Further, a technique is known in which fine grooves are formed in a crossed manner or in a radial manner in a sealing portion that seals an opening of a liquid container, at a position at which the tip of a punch contacts first. Therefore, a hole can be formed on the sealing portion smoothly and a breakage having a uniform shape can be formed in the sealing portion (see, for example, JP-A No. 2007-38537).
On the other hand, when ink including a pigment as a resin component or as a colorant is solidified due to evaporation of a solvent component in the ink, the solidified ink may remain solid without re-dissolving. As a result, the solidified ink may accumulate at a nozzle tip or the like of an inkjet head that discharges ink, thereby blocking the ink discharge or altering the discharge direction. In addition, ease of maintenance of the inkjet head may be impaired due to difficulty in removing the ink attached to the inkjet head by wiping or the like. As a method of facilitating the removal of ink by wiping or the like, a technique of including a moisturizing agent or a wetting agent in ink is known, and urea is known as an example of the moisturizing agent. For example, an ink composition containing urea as a moisturizing agent in order to facilitate removal of the ink composition when it is dried and solidified in the vicinity of nozzles (see, for example, JP-A No. 2009-221253).